The present invention relates to a device for color detection of chemicals and, more particularly, to a hand-held device for rapid colorimetric detection of explosives, narcotics and other chemicals, which device can be accurately operated by non-skilled personnel and can perform numerous tests in a quick sequential manner without exposing a user to hazardous reagents and without exposing sensitive reagents to deteriorating environmental conditions.
Detection of minute quantifies of chemicals on objects may be affected in two alternative strategies.
The first strategy involves sampling an air sample from near the object and chemically analyzing the chemicals present in the air sample using methods such as for example mass spectroscopy, gas chromatography, electron capture, etc. This procedure although quantitative is complicated since the analyzing apparatuses are complex, expensive, in many cases not portable and require power supply. Furthermore, some chemicals, those characterized by low vapor pressure such as for example plastic explosives, are some times difficult for detection using these methods. In these cases sampling of the surface of the object itself is required.
The second strategy involves sampling the surface of the object using a collecting substrate (e.g., a paper or a cloth materiel) and analyzing the collected sample with reagents applied onto the collecting substrate to generate a specifying color reaction when a target chemical is present in the sampled sample.
Principally, the later strategy is more suitable for operation by non-skilled personnel such as guards, policemen and soldiers in airports, border crossings, bus stations and buses, for a simple and quick detection of explosives and/or narcotics.
Nevertheless, sequentially adding reagents onto the collecting substrate for color detection of chemicals suspected to be present on the substrate after sampling is in many cases cumbersome and thus inconvenient to execute under field conditions.
Furthermore, as some of the reagents employed are either sensitive to environmental influences (e.g., light, air, dust, etc.) under which they deteriorate fast, or harmful and thus dangerous to the user (e.g., organic solvents including reagents), thus sampling and color detecting chemicals may become inaccurate and dangerous to the user, respectively.
As terror and narcotic drugs become an ever growing problem worldwide, there is a widely recognized need for, and it would be highly advantageous to have, a hand held device for colorimetric detection of chemicals such as explosives and narcotics, which device can be accurately operated by non-skilled personnel and can perform numerous tests in a quick sequential manner without exposing the user to hazardous reagents and without exposing sensitive reagents to deteriorating environmental conditions.